Cost-Saving Insulated Foundations

Using ICFs to build frost-protected shallow foundations

I poured my first frost-protected shallow foundation (FPSF) in 1976. At the time, I was building affordable houses in mid-coast Maine, and a carpenter suggested we could eliminate the cost of a full foundation and the attendant excavation by using a foundation system pioneered in Scandinavia. We called it a "Swedish slab," although the technique actually originated in Norway (see The FPSF Principle sidebar).That particular frost-protected shallow foundation contributed to a "super-insulated" house. Keep in mind that in the mid-'70s, a super-insulated house was framed with 2x6s and had R-19 walls and R-30 ceilings, which today wouldn't meet Vermont's basic...